内消旋和外消旋2,3-二氰基-2,3-二苯基丁二酸二乙酯在苯乙烯中的分解动力学

用膨胀计方法测定了2,3-二氰基-2,3-二苯基丁二酸二乙酯的内消旋体(1)和外消旋体(2),于不同反应温度,分别在泰乙烯中的分解动力学和活化参数。结果表明,2比1更为稳定。用动力学链长综合常数k′来解释了1和2在较低温度时的单体极限转化率X_∞大于较高温度时的X_∞实验结果。

A Kinetic Study on The Thermal Decomposition of meso-and di-Dietnyl 2,3-Dicyano-2,3-diphenylsuccinate in Styrene

The kinetics of the thermal decomposition of rneso-(1) and dl-dieihyl-2,3-dicyano-2,3-diphenylsuccinatc(2) in styrene at different temperatures were studied by means of dilatometry. The activation parameters were found to be. E_d=93.2 + 3kJ·mol^-1, △S&^#8800;=-12.7+1 eu for 1; E_d=120.8±3kJ·mol^-1, △S&^#8800;= 1.8 ±1eu for 2. The conclusion is that the dl-isomer is more stable than the meso-isomer on the basis of the rate constant for the decompositions and the half life of the two isomers.An explanation is offered for the fact that the final conversion X_∞ of 1 and 2 at lower temperature is larger than that of 1 and 2 at higher temperature in terms of the comprehensive constant k' of the kinetic chain length.